The Ukraine crisis shows that all of Europe should pay more for Nato – Scotland included

Barack Obama will touch down in Estonia today, in a visit designed to reassure the tiny states of the Baltic that whatever happens in Ukraine (where a permanent ceasefire has apparently just been announced), they won't be next to have Vladimir Putin's armies marching into them. The difference, of course, being that while Estonia, was once a satellite of the Soviet Union like Ukraine, today it's a proud member of Nato, and benefit from Nato's three musketeers-style policy that an attack on one is an attack on all.

It will no doubt be a touching scene, a tiny, newly independent democracy getting a timely pat on the back from its tough new big brothers. But what if it was another newly independent democracy, again in a rainy corner of north-east Europe, only this time one that had just insisted that part of Nato's nuclear deterrent be removed from its turf? And whose foremost statesman had once described Nato's bombing of Slobodan Milosevic’s Serbia as "unpardonable folly". Would Nato be as keen to help them out if Russia started eyeing them up?

The nation in question, in case you haven't worked it out, is Scotland, which, according to the latest polls, looks closer than ever to be voting for independence in the referendum on September 18. And the answer, of course, is yes, Nato would still stop Scotland being attacked by Russia, irrespective of whether Alex Salmond presses ahead with his plan to remove Britain's nuclear submarines from Scottish waters. The reason being that Scotland, even if it was run by a government with a stated anti-nuclear policy like the SNP's, would still benefit from Nato protection simply by its proximity to a nuclear-armed England and Wales. Neither Uncle Vlad, nor indeed any other would-be aggressor, would think it sensible to invade Caithness or send "peacekeeping" troops to liberate the Kintyre Peninsula as long as Scotland is still attached to England.

This might, of course, seem like a rather abstract argument, given that were Russia to expand its territorial ambitions beyond Ukraine, it would most likely stop at the Baltics rather than Scotland. But there is nothing abstract about the amount of money Mr Salmond thinks Scottish taxpayers will save if they no longer have to contribute to Britain's nuclear defence budget. According to some estimates, even if Scotland rejoins Nato independently – which will entail a certain minimum defence spending – its defence budget would be at most around £2bn, compared to the £3.3bn the SNP estimates that Scots currently cough up as part of Britain. That's a lot of extra money for schools, hospitals and so on. And at the same time, the SNP can continue posturing as a bunch of gentle peaceniks without ever having to worry about the kind of foreign bullying that Ukrainians have to put up with.

And it isn't the only country that will get by in Nato without paying its full way. It has been a running sore in the organisation for the last few years that the burden of providing Nato's collective muscle is falling disproportionately on a few members. Within the alliance overall, America contributes 73 per cent of the spending, and within the European members, France, Germany and Britain contribute more than 50 per cent. Pressure to trim defence spending, which has increased in the wake of the Eurozone crash, also means that for the last few years, only four countries have met an agreed Nato target that each member spend two per cent of its GDP. They are the US, Britain, Estonia and Greece respectively (although that last one is a legacy of the Greek government's junta-like habit of having a vast army as a job creation scheme).

As the UN Secretary General, Anders Fogh Rasmussen, puts it rather mildly, these gaping discrepancies "have the potential to undermine alliance solidarity". Yet with Russia's incursion into Ukraine no longer deniable by even the most dovish European politicians, it is an issue that may not be dodged much longer. Last week, the Dutch foreign minister, Frans Timmerans, joined the growing chorus of voices in Britain calling for an end to historic cuts to defence spending. And at this week's Nato summit in Newport, Wales, where Ukraine will top the agenda, there will be a whip round for all 28 member states to substantially increase their military budgets.

Whether that will happen, though, is another matter. For most Left-wing governments in Europe, the idea of increasing defence spending while maintaining austerity budgets will be a very hard sell, especially if it's just to ease pressure on nasty old America, the evil invader of Iraq and Afghanistan etc. Few would probably care much, either, for easing the military burdens on Britain or France, the other two nuclear-armed states in Nato, whose arsenals are likewise disdained as imperial legacies.

Yet ultimately, it is those nuclear weapons, as much as conventional ones, that sustain Nato's credibility as a force to be reckoned with. If you don't believe that nukes are still relevant, just ask Putin. Responding to international outrage last week over his latest incursions into Ukraine, he boasted to a group of Russian schoolchildren that the world should not forget that "Russia is one of the leading nuclear powers". He may have been partly joking. But the fact that he even mentioned it says a great deal about how he is dragging Russia back into the "might is right" school of foreign policy.

It would be unrealistic, of course, indeed undesirable, to expect other Nato states to start acquiring nuclear weapons. But they might at least remember that the few Nato members which do so face a political as well as an economic cost. It is a bitterly divisive issue in Britain, as we have seen since the days of CND, and as the current row over the future of nuclear bases in Scotland still proves. Spared that particular headache for themselves, Nato's non-nuclear members might therefore want to think about digging deeper into their pockets when the whip-round starts after Newport. Scotland included.